This chapter reviews literature on agenda setting and the environment, asking what explains the rise and fall of environmental issues on the U.S. policy agenda. It begins with a discussion of agenda denial in an attempt to explain why some problems never make it onto the agenda in the first place. Next, the chapter examines macro trends in U.S. attention to environmental issues since the beginning of the modern environmental movement. Growing attention to environmental problems in the 1960s and 1970s was part of a larger government expansion that left in its wake a robust administrative state that shaped subsequent environmental policy processes. The remainder of the chapter looks at the generation and framing of environmental problems, two processes central to agenda setting. The chapter concludes with some thoughts about where the literature should go next.